When does the collapse of the magnetic field occur in an ignition system?

The collapse of the magnetic field in an ignition system occurs when the ignition system is activated. This process is integral to the functioning of ignition coils, which rely on the principle of electromagnetic induction. When the ignition system is activated, the primary circuit is closed, allowing current to flow through the ignition coil. This builds a magnetic field around the coil.

When the ignition system triggers the opening of the circuit (usually through the ignition control module or distributor), the current flow stops suddenly. This abrupt cessation causes the magnetic field to collapse. As the magnetic field collapses, it induces a high voltage in the secondary coil of the ignition system, which then generates the spark necessary to ignite the air-fuel mixture in the engine’s cylinders.

Understanding this collapse and the timing of the ignition system's activation is critical for diagnosing ignition issues and ensuring proper engine performance.